1. Field of the Invention
The present invention relates to a cutting machine that cuts a plate set on the work area of a table, and more particularly, to a technology for ventilating an exhaust chamber inside the table of the cutting machine.
2. Description of the Related Art
As typical examples of the cutting machines of this type there are thermal cutting machines, such as plasma cutting machines that use a plasma torch as the cutting head, laser cutting machines that use laser torches, and gas cutting machines that use gas burners. When plate material placed on a table is cut using these types of cutting machines, fumes, high-pressure gas and the like (hereinafter for simplicity called “exhaust fumes”) appear in the table from the underside of the plate. As a result, generally, these types of cutting machines have exhaust chambers in the table and discharge exhaust fumes appearing inside the exhaust chambers to outside the exhaust chambers. As technology for discharging exhaust fumes to the outsides of the exhaust chambers, there is, for example, the technology disclosed in JP-B-S60-43231 and JP-A-2003-136248.
JP-B-S60-43231 describes a plasma cutting machine technology involving a smoke path provided inside the cutting table and partitioned at right angles to the direction of movement of a carriage mounting a plasma torch, a pair of suction and blower hoods mounted on the carriage and disposed opposite each other across the smoke path inside the cutting table, and a dust collector mounted on top of the carriage. The suction hood and the blower hood are each connected to the dust collector by ducts, and the dust collector both sucks air from the suction hood via the duct as well as blows air from the blower hood via the duct. In other words, the dust collector acts as both a vacuum, sucking air from within the smoke path, and a blower, sending air into the smoke path.
JP-A-2003-136248 discloses providing a plurality of exhaust chambers in the table, connecting each exhaust chamber to a dust collector via a damper-equipped exhaust duct, and efficiently ventilating fumes getting inside the table during cutting by shifting the open damper with the movement of the head.
According to JP-B-S60-43231, specifically, the dust collector takes up and cleans the exhaust fumes generated in the smoke path and returns the cleansed exhaust fumes back into the smoke path inside the table. In general, the exhaust fumes from plasma cutting are of a high temperature. As a result, although they may be cleaned by the dust collector, when those exhaust fumes are blown into the table their lighter specific gravity creates a rising air current that causes the exhaust fumes to dance upward and leak from the top of the table to the outside of the cutting machine.
Moreover, according to JP-B-S60-43231, the dust collector that is the source of air blown into the table smoke path is present at a location that is separated from the smoke path. As a result, the amount of wind that is sent into the smoke path via the blower hood is not enough to push the exhaust fumes to the vicinity of the suction hood.
Further, according to JP-B-S60-43231, since both the blower hood and the suction hood are provided on the moving carriage, when carrying out cutting that moves the carriage at high speed the blower hood and the suction hood move to the next segment of the table while fumes still remain in one segment of the table, with the result that the remaining fumes leak from the machine.
According to JP-A-2003-136248, a blower such as an electric fan is fixedly mounted on the table in the vicinity of the blower port of each of the exhaust chambers inside the table. According to this construction, the greater the number of exhaust chambers (for example, the longer the table in the direction of alignment of the exhaust chambers), the greater the number of blowers mounted on the table.